Mold for casting metal



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F2 C. CHESTERFEELD v MOLD FOR CASTING METAL Filed March 22, 192.3 2Sheets-Sheet .1

E Tum 2U/Wfl i www f my A1154 P, C. CHESTERFIEED MOLD Fon CASTING METALFiled March 22,' 192s 2 sheet-sheet 2 nl JCL-1. 4

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Patented June 22, 1926. l

, UNITED.- sra'rss PATENT ori-ics PERCY C. CHESTERFIELD, OF DETROIT,MICHIGAN, ASSIGNOB T CHESTEBFIEID METAL COMPANY, OF IDIEITIOIT,MICHIGAN,. A CORPORATION OF MICHIGAN.

MOLD ron CASTING METAL.

Application led Hatch 22, 1923. `Serial No. 626,801. This inventionrelates to improvements from the top of the slab to the cut-away orinmethods of casting alloys andl molds tions or recesses in the bottomthereof. Furtherefor, and,` while not restricted to ther above therecesses cross grooves 13 are such use, arel especially adapted forformed. These grooves are conveniently the manufacture of cutting toolsof selfformed prior to the securing of the cross 60k hardening alloys,such as those composed of piece 1n position.

' both cobalt and nickel or one of these metals lVhen the two slabs arebrought together, singly and one or more members of the a series ofvertical channels are formed conchromium group. v x nected together attheir lower ends so that 10 One of the principal objects of my invenifmolten metal be poured d own the middle 65 tion is the rovision of meanswhereby the \channel it will enter and rise up the side hardness o ,theresultin casting is mainchannels so that five (or more) bars may tainedsubstantially uni orm in spite of be cast simultaneously. y variationsin the rate of solidiication and The metal for which this mold wasparcooling of the metal. ticularly designed shrinks on solidifying so 70A further object of the invention is the that the grooves are madetriangular as provision of an improved form of mold -for shown toprovide wedge surfaces between vproducing castings of metal which shrinkthe cast metal and .the mold which enables on solidication. u the formerto push the two halves'of the It is also an object of the inventionl tolatter a art as the metal shrinks. 'I5 provide a simple forni of moldfor casting The rame which carries these molds is metaL desi ed to allowthe two halves of the Other and further important objects of mol s toseparate in this way. Thus, resttliis invention will be apparent fromthe ing on the pipes 7 are a pair of plates 14 disclosures in thefollowing specification. apertured for the passage of the` stays 6. 80 vOn the drawings.: v On the latter-are arranged sprin s 15 adapt- Figure1 is a side elevationof a battery ed to press the plates 14 towar s theseries of molds embodying the present improveof molds arrangedtherebetween. ments, The pressure exerted on thel molds by Figure 2 isasection on the line 2-2 of these springs may be adjusted by means of8.5

Figure. 1, a further plate 16, also slidable 0n the stays Figure 3 is across-section through an in- 6, against one side of which one set ofdividual mold after the metal has been cast. springs 15 bear and againstthe other side Figure 4 is a front elevation of one half of which bearsthe screw 17. This screw of a modified form of mold. 17 and plate 16also enable the ap aratus 90 Figure 5 is a section on the line 57-5 ofto be used with a varying number o molds, Figure' 4. as desired.

The apparatus comprises a frame to carry1 While these molds arepreferably cona battery of molds for the metal to be cast. structed ofgraphite, they may also be made The frame consists of a pair of endplates of cast iron, in whichcase the molds are 95 5 secured in spacedrelation bystays 6 and treated before use with a solution of sula pairof bars or tubes'7 which actas the phuric acid to prevent the hot metaladhersupports for the molds. ing thereto.

The molds are preferably made of graph- Graphite is, however, muchsuperior to ite slabs 8 and 9. These slabsare cut away cast iron as amaterial for molds. In 100 at one end and in the cut away portion of thefirst place it is much easier to machine one slab (as -8) is secured acrossfpiece of graphite than cast iron so that molds for graphite 10 adatedto enter the correspondcasting special sizes and shapes can be moreing recess in t e other slab. This cross readily made. Then again, castiron molds )ieee may conveniently be held in position have to berepeatedly treated with sulphuric 105 liy wood screws 11 and also b asuitable acid solution since the effect of the treatcement such Vas amixture of so ium silicate ment soon wearsroff.

solution and graphite. Further, cast iron molds, especially7 for In theabutting faces of the slabs are cut small sizes of bars, chills the metatoo grooves 12 of triangular section extending rapidly. This chillingmakes the bars hard 110 and, while should be uniform. throughout the barand chilling makes the out-er layers harder than the center.

Now graphite has a lower specific heat per unit volume of that ofthe'latter material. Further, the heat conductivity of graphite is only11% of the heat conductivity of cast iron. Conso uently the rate ofabstraction of heat from t e cooling metal is far less in the case ofgraphite than in the case of cast iron molds.

Graphite has the additional advantage of giving a very smooth surfaceamost im- Eortant desi'deratum in the casting of selfardening alloys, asthe only way the latter can be worked after casting is lby grinding andthis is a slow operation in view of the extreme hardness of the-alloys.

Where elasticity in thermold is required, as'vvhere rings have to becast and the core must compress to allow for the contraction of theparts, raphite is especially useful..

Where sang molds are used, even if brushed over with graphite powder,the bars are full of blow holes and the metal is too soft for use as ahi h-speed lathe tool.

Whether the mov ds are made of graphite or cast iron, they should beWarme before use, and for this purpose a series of gas jets 18 arearranged beneath the molds. To conserve the heat of these jets, a hood19vmay conveniently be used to cover the apparatus While it is beingwarmed prior to use and then removed by handle 20v for the castingoperation. l

Above the central channel of each mold a gate 21 is placed to'act as afunnel for the cast metal. These gates, which may convenien'tly be madeof cast iron, are made in two halves detachably held together by clips22.

The mold shown in Figures 4 and 5 is adapted :tor castingrings. ln thiscase one half' 25 of `the mold is formed With a circular recess-26having a shoulder 27 formed therein for engagement with the periphery ofan annular core 28. This core is ont diagonally, as at 29, like a pistonring, so that as the metal cools the ring may compress and close thisslot.

The other halie of the mold is a. plain slab of graphite 29 adapted toseal the annular space around the core 28. A roove 30 is formed in thehalf-mold 25 for the passage of the molten metal into such annularspace, and a groove 31 for the'escape of air therefrom. in connectionwith Ithese molds, as in the previous forms, a casting gate t2 isprovided.

By this construction a ring may be cast having a cylindrical innersurface. lf the core 'were not com ressible, it would be necessary tomake the core conical to allow hardness is a desideratum, it

than cast iron, beingl only7V neeaee'e ma be used. After a nick has beencut in eac side the intervening metal is fractured by'va sharp blow witha hammer. The bars are then smoothed and ground to the desired form bycarborunduin or other abrasive wheels.

The alloy for which the above mold is more particularly designed'fis onecomprising cobalt and/or nickel and one or more of the metals of thechromium group.

y A suitable alloy is one whose metallic component-s consist .of s

, per cent. Nickel 14 Cobalt 27 Chromium 3l Tungsten 28 To the aboveconstituents is added a har ening element, such as carbon, either freeor as a carbide.

Certain of the c'arbdes are excessively hard, for example, boron carbideand titanium carbide are the only tvvo substances known at present which.are hard enough vto cut diamond. Similarly, silicon carbide andtungsten carbide are suiiciently hard to scratch corundum, Whilechromium carbide will scratch to as.

l have foun that additions of boron carbide and titanium carbide givebetter and more uniform results than carbon alone, and preferabltherefore, il use one or other, or possib y both, of these tivosubstances or any other carbide which may be found hereafter having agreater hardness than silicon carbide. Silicon my also be used in somecases,'added either in the free state or as the carbide.

l have also found that the hardness of bars cast from the above alloyvary accord# ing to the rate at which they cool so that a small bar,`which necessarily cools more rapidly than a large'one, is, otherconditions being the same, harder. @n the other hand, `increasing thecarbon content of the alloy increases its hardness. lt has further been.found that heat treatment of the alloy after casting does notappreciably change the hardness so that the alloy may be termedselhardening 'lo secure the. best results it is necessary to vhit thehappy mean between too great this purpose a cuta ting-.olf Wheel ofcarborundum or the like tol iti@

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from the Crucible, it is the Crucible,

bility to flake or chip,

which means brittleness, and liaand too little hardness, which meansthat a tool made therefrom willbe too soft' to cut for the desiredlength of time or to cut hard metals.-

This I 'accomplish by the present inventio'n by varying the amount ofhardening element, such as boron carbide, added with varying dimensionsof the bar to be cast.

For example, for a 1A; inch bar 0.56% boron carbide lnay be used toadvantage; for a 1%; inch bar 0.85%; and for a l@ inch bar 0.97

By so varying the content .of boron carbidethe sum of thehardness due tochilling and the hardness due to the hardening element. is maintainedsubstantially uniform irrespective of the size of the bar cast.

In addition to the carbon added, as boron carbide, there is also acertain carbon content in the constituent metalsand a further smallquantity of Carbon is picked up from the Crucible if an unlined graphiteCrucible be employed.

As aresult ofjthe picking up of carbon desirable to avoid heating themetal too much or too long in .and further, when remelting scrap alongwith a proportion of new metal, to reduce the amount of boron carbideadded to carbonize the latter.

I Claim as my invention:

1. A mold for casting metal comprising a pair of uprights, a pair ofrods connecting the upper portions of said uprights, a second pair ofrods Connecting the lower portions of said uprights, a mold comprisingtwo vertical sections adapted to slide vertihardness,

cally between the rst pairof rods and to rest-upon the second pair ofrods and releasable means for holding the two sections of the moldtogether..

2. A mold for casting metal comprising a pair of uprights, pairs of rodsconnecting the upper and lower portions of said uprights, a moldcomprislng two vertical sections between said uprights, means forsupporting said mold, a plate having apertures for the passage of saidrods and slidable thereon adapted to engage one section of said mold, asecond plate having apertures forv the passage of said rods and slidablethereon, coiled springs around each of said rods between said plates andmeans for adjusting the position of the sec-ond plate to the adjacentupright.

3. A mold for` casting `metal comprising a pair of uprights, pairs ofrods Connecting the upper and lower portions of said" uprights, a moldcomprising two vertical sections adapted to slide vertically betweensaid pairs of rods, a further pair of rods between said uprights lbelowand between the lowermost ot' the first mentioned pairs of rods forsupporting the mold, a plate having apertures for the passage of saidrods andv slidable thereon adapted to engage one section of said mold, asecond plate having apertures for the passage of said rods and slidablethereon, lcoiled springs around each of said rods between said platesand means for adjusting second plate to the adjacent upright.

4. A mold for casting metal comprising a pair of uprights, rodsconnecting" sai uprights, means for supporting a mold oomprising twovertical sections between said upriglits, a pair ofplates slidable uponsaid rods, one of said plates contacting springs on said rods betweensaid plates, and means for adjusting the position of the other platerelatively to the upright adjacent thereto.

5. A moldfor casting metal comprising a pair of graphite slabs, each ofsaid'slabs being recessed at one end, a strip of graphite arranged inthe recess of one slab and secured thereto and adapted to enter thecorresponding recess in the other slab, and a longitudinal groove in oneslab for the reception of the metal to be Cast.

6.. A mold for castingm'eta'l comprising a pair of plates, one of theplates having an oi'set portion adapted to enter a recess in the otherplate, said last mentioned plate having a groove therein extendingtransversely with respect to the offset portion for the reception of themetal to be cast, said groove extending to said recess and being closedat its lower end by said offset portion when the plates are inengagement with each other.

In testimony whereof I have hereunto subscribed my name.

PERCY C. CHESTERFIELD.

the, position of the

